Typically, a navigation device (be that an in-vehicle navigation device (i.e. a navigation device built into a vehicle and which cannot be removed from that vehicle); a PND such as a TomTom® Go 720 or similar; or a mobile telephone, personal digital assistant (PDA) or computer (e.g. a PC) executing navigation software) is configured to display an image that includes a map view generated from a digital map. The map view may be superposed with route information depicting a navigation route, and whilst this route information may be pre-recorded, it is more typically the result of a route-planning algorithm executed by the navigation device using suitable software. The navigation device may also include or interface with a position determining system (such as Global Positioning System (GPS)) for determining the current real-time position of the navigation device, and for dynamically adjusting the map view in accordance with the determined current position.
A popular type of map view is a two-dimensional-based map view that includes information in two-dimensions at ground level. For example, roads and buildings are represented by the shape of their footprints on the ground. Such two-dimensional information may be viewed as a plan (i.e. looking generally vertically downwardly on the map, in the same manner as a traditional paper map), or in artificial perspective as if viewing a traditional flat paper map from a perspective angle. However, in either case, the map view is generally “flat” in the sense that the information displayed is only two-dimensional ground level information, and references hereafter to a two-dimensional plan view should be construed to include both of these types of map view.
Particularly in the context of in-vehicle use, it is generally desirable to provide a highly intuitive navigation display that (i) provides the driver with current navigation information, and (ii) provides an indication of the future route, so that the driver can drive and position the vehicle appropriately.
It has also been previously proposed to provide other information to the driver that could potentially be of use. For example, it has previously been proposed to display points of interest (such as banks, petrol stations or public facilities) that are on or close to the route, street names for roads on or close to the route, and icons representing the location of speed limit enforcement cameras that are on the chosen route.
Whilst the provision of these additional items of information can often be of use to the driver, it is important that the driver is not provided with so much information that the route becomes difficult to follow or the driver is distracted by the amount of information displayed.
One simple way to avoid the problem of inadvertently overburdening the driver with information would be to provide this additional information only when the driver requests it, for example by touching the screen of the PND. However such an arrangement would require the driver to take at least one hand off the wheel of the vehicle to operate the PND. Whilst a driver should only do this whilst the vehicle is stationary some drivers will doubtless choose to attempt to operate the PND whilst moving, with potentially adverse consequences.
Clearly there is a fine balance to be drawn between providing the driver with information that might be of use and not overburdening the driver with information to such an extent that the driver's attention is distracted from safely operating the vehicle in which the PND is provided. The present invention has been devised with the aim of addressing these contradictory issues.